MANUFACTURE OF SULPHATE OF COPPER. 
235 
form from its solution in alcohol, which might easily have been 
done, since the amount of oil examined yielded a quantity quite 
sufficient for the purpose. 
The undistilled residuum was next examined. Its specific 
gravity at 66° was 949, only. It left a fixed stain upon paper, 
which (as it was perfectly soluble in 80° alcohol) was probably 
owing to a further admixture of resinous substances. An addition 
of this kind would very naturally suggest itself, to correct the lim- 
pidity occasioned by such a copious admixture of diluents. 
Since the above examination was made, another sample of the 
same substance from a similar source, was found to contain an 
adulteration to the extent of nearly 70 per cent., consisting mainly 
of oil of turpentine. Its specific gravity was 902. — New York 
Register of Medicine and Pharmacy \ April 1, 1851 
MANUFACTURE OF SULPHATE OF COPPER. 
The commercial manufacture of sulphate of copper, and the ap- 
paratus employed, is very simple. In a wooden vessel lined with 
stout sheet-lead, a certain quantity of oil of vitriol is . introduced, 
to which copper-scales are added, until a saturated solution of sul- 
phate of copper is obtained, the operation being assisted by the aid 
of steam, blown in through a lead pipe dipping to the bottom of 
vessel ; the mother-liquor of a previous operation is then added, 
and the whole set aside to crystallize. The crystallizing vessels 
are of wood lined with lead. These are placed in a warm room, 
and a crop of crystals is usually obtained in the course of four or 
six days. The mother-liquor being poured off, the crystals are 
placed in the drainer, after which they are dried, and packed in 
casks for sale ; or, what is of more frequent occurrence, taken from 
the drainer whilst still damp, and in that state packed for sale. 
The copper-scales above mentioned consist of a mixture of me- 
tallic copper with oxides of that metal, and are obtained in the 
form of thin plates or scales from the sheets of copper which have 
undergone the process of annealing, by being heated in a furnace 
or forge. A poition only of these scales are dissolved by the sul- 
phuric acid ; the residue is therefore washed, dried, and sent to 
